According to Best Buy's Gamer Club twitter account, the exclusive Meta Knight amiibo won't even make it to the store shelves. Pre-orders have accounted for their entire inventory, so they won't have any left to put into the stores at all.
So if you missed the pre-order, and were hoping to maybe pick one up in store, you won't be able to.
Looks like I'll be trying to obtain a Meta Knight from elsewhere. Sigh.